PURPOSE: To obtain an object which is excellent in dielectric property and copper foil exfoliation strength by using mixed unwoven fabric consisting of fluororesin and heat-resistant engineering plastic fibers, and getting an insulating layer wherein this is combined with low permittivity thermosetting resin which includes hardening matter of specific permittivity.

CONSTITUTION: Fluororesin fibers consisting of polytetrafluoroethylene, tetrafluoroethylene, hexafluoropropylene copolymer, olefin-tetrafluoroethylene copolymer, etc., and heat-resistant engineering plastic fibers such as omniaromatic polyamide, polyphenylene sulfide, etc., are mixed at specified rate and are used as base material of mixed unwoven fabric. It is suitable that an insulating layer, wherein cyanate resin and thermosetting resin with low permittivity of 3.5 or less at 1MHz, wherein high boiling point compounds, wherein 2 to 7 pieces, on an average, of aromatics which are nonsubstituted or substituted for halogen atoms or low-grade alkyl groups are coupled in a straight chain shape, are arranged to the cyanate, are combined, should be used. Material for printed wiring, which is excellent in dielectric property and in which shrinkage in laminate formation is small and which does not bring about exfoliation, can be obtained.